Rear Axle System Off message
Thread Starter
Instructor
Joined: Oct 2024
Posts: 132
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From: Boston
Rear Axle System Off message
Well well well. Just took my 2024 2LT Z51 (3,064 miles) off the street and into the driveway and got this gem on the dash. Once in the driveway I noticed the message but no CEL. I shut it off and restarted it to the same message AND a CEL. I pulled codes and got P0700 and P2818. Restarted twice more with the same result. I'm going to let it sit overnight and see if it was a glitch, but I don't know if my optimism is at peak performance right about now! I guess the P2818 could be a stuck solonoid. Has anyone had this happen and what were your results? (I noticed the eLSD guage is reading 0)
Race Director
Joined: Mar 2007
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P2818
Transmission Control Solenoid Valve 3 = Off
Frequency the DTC runs = Continuously - After the running conditions are met
Conditions for Setting the DTC
P2818
B12BD Transmission Fluid Pressure Sensor 4 = Greater than 100 kPa (14.7 PSI) - For greater than 1> s
Actions Taken When the DTC Sets
Limited Slip = Not Available (I think this is the source of the Rear Axle System Off message
Transmission Control Solenoid Valve 3 = Off
Frequency the DTC runs = Continuously - After the running conditions are met
Conditions for Setting the DTC
P2818
B12BD Transmission Fluid Pressure Sensor 4 = Greater than 100 kPa (14.7 PSI) - For greater than 1> s
Actions Taken When the DTC Sets
Limited Slip = Not Available (I think this is the source of the Rear Axle System Off message
Race Director
Joined: Mar 2007
Posts: 11,244
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Here's that info. Doesn't make complete sense to me, but it all has to do with fluid pressure measurements in the differential it appear. I did not check, but most of the valves and sensors are in one of the two valve bodies.
C2A19 DTC Descriptor
Limited Slip Differential Pressure Too Low
C2A19
Transmission Fluid Pressure Sensor 4 = Less than a predefined threshold - For greater than 1> s
P2817
Conditions for Running the DTC
P2817 Transmission Control Solenoid Valve 3 = On
P2817
B12BD Transmission Fluid Pressure Sensor 4 = Pressure increase is less than a predefined threshold
Actions Taken When the DTC Sets
Limited Slip = Not Available
C2A19 DTC Descriptor
Limited Slip Differential Pressure Too Low
C2A19
Transmission Fluid Pressure Sensor 4 = Less than a predefined threshold - For greater than 1> s
P2817
Conditions for Running the DTC
P2817 Transmission Control Solenoid Valve 3 = On
P2817
B12BD Transmission Fluid Pressure Sensor 4 = Pressure increase is less than a predefined threshold
Actions Taken When the DTC Sets
Limited Slip = Not Available
Thread Starter
Instructor
Joined: Oct 2024
Posts: 132
Likes: 119
From: Boston
Thanks ANdy. These seem to be what the service techs reference. Any information is good information to me. may be a reach but it was 100 degrees and high humidity out here today and I'm hoping it was a glitch. Also, I got a few notifications for a software update but declined to install it. After a few times, it said I'd have to take it to a dealer to have them do the update. I'm hoping more that its as simple as that. Butttttttttt as we all know dealing with these advanced electronic based cars, something always seems to be popping up.
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Le Mans Master
Joined: Aug 2002
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From: Naples Florida
That stinks, thats a long wait just to find out what is wrong it. When I had my 2025 Z51 I had the same message pop up. I restarted the car and it went away and never came back. Did you try disconnecting the battery?
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Thread Starter
Instructor
Joined: Oct 2024
Posts: 132
Likes: 119
From: Boston
I let it sit for a day and it only pulled the P2818 (Pressure Control Solonoid) and U16F (Lost comm with rear HVAC Module). I cleared them. Let the car sit. Then took it for maybe a 5 mile drive and the lights did not come back nor did the Rear Axle System Off message reappear. Today I'm going to take it maybe 20 miles as I want to stay close to home.
Racer
Joined: Jun 2022
Posts: 424
Likes: 379
Hey OP, whatever happened with your car? My car just gave me that same dash error msg and the dealer says it's throwing a p2818 code. But the car drives fine and has not showed the fault again since first display late yesterday.
Any insights appreciated.
Any insights appreciated.
Advanced
Joined: Jan 2026
Posts: 64
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From: GA
Google says P2818 is "Pressure Control Solenoid 'H' Stuck On". This is a transmission issue. The dealer says it threw the code but did not recommend any action be taken? Weird.
Thread Starter
Instructor
Joined: Oct 2024
Posts: 132
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From: Boston
I forget to update afer bringing it to the dealer. Sorry. The car ran completely normal after throwing the codes and showing the Axle System message, but I wasn't taking any chances. I brought it to MacMulkin in NH (where I bought it...thankfully I'm close), they ran diags on it, and out of precaution they changed out all the valve bodies. Serviced in July and drove it until December when I put it away for the winter with no issues or CEL's.